Another X31 mainboard died ...

[herbs]

Hi Forum,
I havent posted here yet since I havent had any issues with my Thinkpads I couldnt help myself with. But now my favorite X31 has some problem with the mainboard.

The X31 doesnt show the splash screen when I turn it on. This happens with the battery as well the power supply connected. The harddisk runs, the battery and power LED is on. Blank screen though.

I switched the RAM banks for a test, they seem to be ok. Also I tried to disconnect the WIFI module - no change.

Next thing I changed were the notorious capacitors - http://kuzyatech.com/fixing-an-ibm-thin ... mment-7652 - still the same symptoms.

One thing is remarkable - if I leave it running (on battery) for about 20 minutes - switch it off and on again - it works perfectly! Like some component has to warm up to run.

Any ideas to revive this mainboard? Or is it a case for replacement?

Thanks!
herb langhans

[rkawakami]

Welcome to thinkpads.com!

First question: When the screen does finally light up, is there a pink / red hue to it for several seconds? If so, that indicates a dying backlight in the LCD panel. About the only thing you can do is replace the panel. It is possible for the backlight to be swapped out but it's a fairly delicate procedure. The simplest fix is just changing out the screen. If the screen is bright and white, then the problem could be in several other places beside the motherboard:

- the LCD cable
- the lid switch
- the inverter card
- the backlight in the LCD panel

The LCD cable plugs into the motherboard and is routed up into the lid assembly. Besides providing the video signals to the LCD panel, it also powers the inverter. The inverter card takes a small DC voltage and steps it up to a fairly large AC voltage. It is located behind the LCD bezel, just below the screen. The output from the inverter goes directly to the backlight (aka, CCFL) inside the LCD panel. The lid switch controls the power to the inverter; if depressed, it will cut off power and thus turn the backlight off.

I would recommend the following:

- ensure that the lid switch is not stuck; push it down several times quickly
- ensure that the LCD cable is fully plugged into the motherboard, does not have any breaks / tears / cracks
- ensure that the inverter card is fully plugged into the LCD cable
- ensure that the plug to the backlight is fully inserted into the inverter

All of this simply requires some time to take the system apart (i.e., no cost). It sounds like you already have the Hardware Maintenance Manual for the X31 but in case you don't you can find it here:

http://support.lenovo.com/en_US/product ... MIGR-44018

If that doesn't fix the problem, then it's time to start throwing $$$ at it. The first thing I would change is the inverter. If that's not the problem, then consider another LCD panel. Please note that the source of the problem could still be something on the motherboard. Swapping out the inverter and panel with known good units would determine where the problem is.

[herbs]

Hi Ray,
thanks for your quick reply.

I probably guided you in the wrong direction. I wrote that the harddisk is running, but actually it just has power, spins, and doesnt start the boot sequence (I would hear that, also the blinkenlight were flickering).

The display doesnt show a reddish hue, lid switch seems ok (goes on and off when I operate it with the open screen once the X31 is running). Probably all fine there unless the LCD-unit is able to pull the whole startup sequence down.

At the moment I have it running, I type this on my X31

The more I play with it I get to the idea there is some thermal problem. I already took out the RAM banks, and cooled them down with the freez-o spray. But once the mainboard is warmed up (cold RAM in), it just starts and runs as it should do. Most thermal problems are opposite though - something hangs up when the system warms up. My laptop needs to be warmed up to run, in cold state it doesnt boot . Also it wont be easy to find replacement components unless its some resistor, diode or capacitor is bad.

It looks rather like some issue with the initial reset sequence.

Next I will take the mainboard out completely, try to boot it (after some initial black-screen-warm-up sequence), cool down various components and try to boot again.

Good idea?
Cheers!
herb langhans

[rkawakami]

Ah... so it sounds like the system is not booting at all until it's sufficiently warmed up. You should also try attaching an external monitor and see if there is any activity there while the LCD is not showing anything.

If it is a thermal problem, you could help it start up by heating the system with a hair dryer. Or, as you suggest, once it is running, shooting some freeze spray at small areas of the motherboard. If it is a main power problem, I would concentrate on the Analog Devices chips like ADP3806 and ADP3415 and Maxim chip MAX1845. Those are probably some of the common power chips in the system.

[herbs]

Thanks for the hints, Ray! Valuable knowledge you share!

I see these chips down there at the battery connector. But for now I need a little break (wrapping the kids presents, you know). Searching for hardware gremlins requires meditative mood.

Will be back in a few days, thanks a lot.
*** Merry Christmas ***
herb langhans